Common: move EnrichmentConf into its own module (close #303)

modules/common/src/main/scala/com.snowplowanalytics.snowplow.enrich/common/enrichments/registry/IabEnrichment.scala

@@ -13,7 +13,7 @@
 package com.snowplowanalytics.snowplow.enrich.common.enrichments.registry
 
 import java.io.File
-import java.net.{InetAddress, URI}
+import java.net.URI
 
 import cats.{Id, Monad}
 import cats.data.{NonEmptyList, ValidatedNel}